1. Field of the Invention
The present invention relates to an applicator for a tampon to be employed when a sanitary tampon is to be inserted into a human body.
2. Description of the Related Art
The applicator for the sanitary tampon is constructed to include an outer cylinder for fitting the tampon therein, and an inner cylinder inserted into the outer cylinder and protruding rearwardly from the rear end of the outer cylinder. A take-out cord extending from the tampon, is led out of the outer cylinder through the inner cylinder and protruded rearwardly from a rear end of the inner cylinder.
When the tampon is to be employed, the outer cylinder is inserted into a vaginal cavity, and the inner cylinder is pushed to push the tampon out of the outer cylinder. Then, the tampon is inserted into the vaginal cavity while expanding a number of deformable valves at the leading end of the outer cylinder.
Some of the existing applicators are formed to have an outer cylinder and an inner cylinder which are made of paper. In recent years, however, an outer cylinder injection-molded of a synthetic resin has been employed so that it may have a smooth surface and may be smoothly inserted into the vaginal cavity.
FIG. 4 is a partial side elevation showing an ordinary shape of the leading end portion of an outer cylinder 30 of a conventional applicator.
The outer cylinder 30 of the conventional applicator is constructed to include a cylindrical large diameter portion 30a, and a curved face portion 30b is formed on the side of the leading portion with respect to the large diameter portion 30a through an inflection point Zo. The curved face portion 30b is formed into a generally semispherical shape which has a radial center located at the center O of the section extending through the inflection point Zo. Therefore, a ratio Ao/Bo is about 1, if the radius of the outer periphery at the inflection point Zo is designated by Ao and the axial length from the inflection point Zo to the leading end of the curved face portion 30b is designated by Bo.
In the curved face portion 30b, there are formed a plurality of valves 31 extending toward the leading end and arranged in a petal shape. These valves 31 are deformed to converge toward the leading end at the curvature of the curved face portion 30b. 
However, in the shape of the leading portion of the outer cylinder 30 of the conventional applicator for the sanitary tampon as shown in FIG. 4, the large diameter portion 30a has the cylindrical shape, and the semispherical curved face portion 30b is formed at the leading end of the large diameter portion 30a. Accordingly, upon using the applicator, this shape exerts restrictions on the reduction of the resistance to the insertion into the vaginal cavity.
Therefore, the resistance to the insertion into the vaginal cavity could be reduced, if the leading end of the outer cylinder was formed not into the semispherical shape but into the shape in which the diameter is gradually reduced toward the leading portion, that is, in which the ratio Ao/Bo is smaller than 1.
However, if the leading end of the outer cylinder is formed into the shape in which the diameter is gradually reduced, the valves 31 have to be accordingly elongated in the axial direction. If the axial length size of the valves is thus enlarged at the leading portion of the outer cylinder, the shape of the leading ends of the valves is not stabilized but may be deformed to open the leading ends of the valves when the valves are thermally deformed into the curved face shape with the tampon being fitted in the outer cylinder. If the valves are opened, the leading portion of the outer cylinder may give an unnecessary resistance to the human body or may damage the body when the leading portion of the outer cylinder is inserted into the vaginal cavity.
In order to use the valves each having a long axial length and to stabilize the shape of the thermally deformed valves, it is necessary to thicken the outer cylinder itself or to injection-mold a highly hard resin. With the increased thickness, however, the amount of resin to be employed increases to cause a problem that the environment is adversely affected by the dumped resin. On the other hand, if the hard resin is employed, the values become hard to increase the contact resistance to the body. Furthermore, the fluidity of the resin in the injection mold is reduced to easily cause the defective molding of the valves and the like.
The invention has an object to provide an applicator for a tampon in which valves provided at the leading portion can be easily molded and can be prevented from opening at the leading ends, when the leading portion of an outer cylinder thereof is shaped to be easily inserted into a vaginal cavity.
According to an aspect of the invention, an applicator for a tampon may comprise: an outer cylinder including a large diameter portion for fitting a tampon therein, a small diameter portion provided on the side of a rear end of the outer cylinder and having a smaller diameter than that of the large diameter portion, and a plurality of valves provided on the side of a leading end of the outer cylinder, the valves being converged to have a curved face portion to be diametrically gradually reduced toward the leading end of the outer cylinder; and a push-out member movably inserted into the small diameter portion of the outer cylinder,
wherein a ratio A/B is at most 0.8, when an inflection point for the boundary between the maximum diameter portion of the large diameter portion and the curved face portion is designated by Z, a radius of the outer face at the inflection point Z is designated by A, and the axial length from the inflection point Z to the leading end of the curved face portion is designated by B, and
wherein a ratio L/W is within a range of 1.0 to 2.0, when the width size of root ends of the valves is designated by W and the length of the valves is designated by L.
According to the invention, the curved face portion of the leading portion is shaped such that the ratio A/B is at most 0.8, so that it is possible to reduce the resistance to the insertion into the vaginal cavity in comparison with the conventional outer cylinder having the semispherical curved face portion as shown in FIG. 4.
In this case, the valves will be elongated in the axial direction of the outer cylinder. However, by shaping the valves to have the ratio L/W within the range of 1.0 to 2.0, i.e., by securing a large width W of the root end with respect to the length L, the force for holding the resin distortion upon thermally deforming the valves into a curved face shape can be intensified to restrain the restoration so that the valves can be suppressed from being opened at their leading portions.
On the other hand, the root ends of the valves are located substantially at the same position of the inflection point Z.
In the curved face portion, moreover, it is preferred that the curved face portion has two curvatures, and the curvature at the leading end portions of the valves is larger than that at the root ends of the valves.
In this case, it is preferred that the axial length Y of the valve portions having the larger curvature is one half or less than the axial length B from the inflection point Z to the leading end of the curved face portion.
In the leading portion of the large diameter portion of the outer cylinder, the leading end portions of the valves are deformed at the large curvature, so that the plastic deformation of the leading end portions of the valves can be enlarged to further suppress opening of the leading ends of the valves. Since the leading end portions of the valves are formed to have the large curvature, they are prevented, when inserted into the human body, from abutting against the body, thereby giving no uncomfortable feeling to the body.